Agrochemical formulations are generally designed based on customer needs and the physiochemical properties of the active ingredients, for example, the solubility of the active ingredient in water or non-aqueous solvents. There are two major categories of formulations, solid formulations and liquid formulations.
Granule products containing agricultural active ingredients represent one class of solid formulations that are seeing increased use today because of their relative safety compared to liquid formulations and because of the advantages they offer with regard to cost savings in packaging and transportation. Granule products, e.g., in the form of emulsifiable granules (EG), water dispersible granules (DG), and granules (GR) for broadcast application may be used for insect, weed, fungal pathogen and nematode control and are often used in soil and aquatic environments. Because of the particle weight, granules used in aerial applications may pose a reduced hazard from off-target drift compared to aerial liquid spray applications.
Powder or wettable powder (WP) products containing agricultural active ingredients represent additional classes of solid formulations that are also used in agriculture and differ from granules primarily by their smaller particle size. Granules typically have a size range between about 200 to about 4000 micrometers (Wikipedia: Granulation—making of granules) and are much larger than the particles in powder formulations and therefore present less of a respiratory hazard. Granule products may be produced from powders or wettable powders in a granulation or agglomeration process.
Active ingredients, in the form of solids or liquids, may be formulated as granules, and include insecticides, herbicides, fungicides, nematicides and plant growth regulators. Granule formulations usually contain a relatively small amount of the active ingredients since the granules are frequently not further diluted with a carrier solvent such as water prior to use, but are instead applied directly to the area of interest, such as, for example, soil or water. Once applied, the active ingredients contained in the granules are released to the area of application, typically upon exposure to water.
Agricultural granules containing active ingredients also contain solid inert ingredients that may serve as a diluent and/or help maintain the granules in a stable, solid state. These solid inert ingredients may include, for example, clays, starches, silicas, sulphates, chlorides, lignosulfonates, carbohydrates such as dextrines, alkylated celluloses, xanthum gums and guaseed gums, and synthetic polymers such as polyvinyl alcohols, sodium polyacrylates, polyethylene oxides, polyvinylpyrrolidones and urea/formaldehyde polymers like PergoPak® M (registered trademark of Albemarle Corporation). The active ingredient(s) contained in a granule may be melted into a liquid, dissolved in a solvent or dispersed in a liquid, which may then be sprayed onto or absorbed into the solid inert ingredients. In the absence of effective solid inert ingredients, dry granules may be physically unstable and, in the case of solid particles, slowly breakdown forming a dust or powder or, in the case of granules containing liquid built-in adjuvants, slowly breakdown forming large liquid droplets as a result of Ostwald Ripening. Many solid inert ingredients used in agricultural granule formulations generally have good water solubility or dispersibility.
Rice is an important cereal crop grown in many parts of the world and is cultivated under both wet and dry conditions. Control of weeds in rice is very important in order to maintain high levels of agricultural productivity. Use of herbicide granules for weed control in flooded rice paddies and fields is a very common agronomic practice in many rice growing regions. New herbicide granule products that offer improved performance relative to current products are needed.
Cyhalofop-butyl, (2R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]propanoic acid butyl ester (CAS#122008-78-0), is a member of the aryloxyphenoxypropionic acid class of herbicides, which are known in the art as the fop herbicides, and is used to control grass weeds in rice. Cyhalofop-butyl is marketed as Clincher® herbicide (registered trademark of Dow AgroSciences LLC), and is sold in granule (GR), oil in water (EW) and emulsifiable concentrate (EC) formulations, and exhibits good selectivity to rice when used in both dry land and flooded paddy applications.
Existing commercial granule formulations of cyhalofop-butyl contain relatively large amounts of solid inert ingredients such as potassium chloride, clay or starch combined with relatively small amounts of built-in adjuvants such as aromatic solvents. The limited built-in adjuvant content of current granule products can limit the biological performance of cyhalofop-butyl herbicide due to a minimal herbicidal adjuvant effect.
Described herein is an improvement to the herbicidal granule or powder compositions disclosed in U.S. Patent Application Publication 2012/0015811A1, published Jan. 19, 2012. Such improved compositions show improved storage stability in various environments and offer acceptable herbicidal efficacy when used to control weeds in flooded rice paddies or fields, or other crops.